Walk behind lawn mowers are well known for mowing grass. Such mowers comprise a movable cutting deck having a cutting chamber that carries a substantially horizontal rotary cutting blade. A handle extends upwardly and rearwardly from deck the deck. An operator grips the handle and walks behind the mower to guide and control the mower.
The cutting chamber is formed on the underside of deck 4 and includes a top wall and a downwardly extending, peripheral side wall. The cutting chamber has an open bottom facing the ground so that the blade rotating inside the cutting chamber can contact and sever grass as the cutting chamber moves over the ground. The cutting chamber is often shaped as an annular channel extending around most of the periphery of the cutting chamber adjacent the sidewall of the cutting chamber. The grass clippings created by the blade will circulate through at least a portion of this annular channel before leaving the cutting chamber through an exit tunnel.
The exit tunnel receives the grass clippings from the cutting chamber and conducts the grass clippings to a rear discharge opening on the exit tunnel. The grass clippings are often collected in a grass collector when such a collector is connected to the discharge opening. This is the collecting mode of operation of the lawn mower. Alternatively, the rear discharge opening of the exit tunnel can be selectively closed by a pivotal mulch door to retain the grass clippings within the cutting chamber for downward discharge into the cut grass path. This is the mulching mode of operation of the lawn mower. U.S. Pat. No. 7,367,174, assigned to the assignee of this invention, discloses a lawn mower that is selectively convertible by the user between collecting and mulching modes of operation through the use of a pivotal mulch door in the exit tunnel.
While mowers having pivotal mulch doors are known, the mulch doors are often operated by linkages that are fairly complicated and obtrusive. Many of these linkages are often contained on the exterior of the mower and include numerous parts. This leads to extra expense in manufacturing the mower and decreases the aesthetics of the mower. There is a need in the art for a mulch door that can be operated by a simple and durable mechanism that is largely hidden within the mower. The operating mechanism should be conveniently located and easy to operate by the user. The operating mechanism desirably should also securely lock or retain the mulch door in the open or closed positions thereof.
In addition, the performance of the mower in both its collecting and mulching modes should be optimized to the maximum extent possible despite the presence of the mulch door. Often, mowers that are convertible between collecting and mulching modes might work well in one mode but not the other, i.e. they might be a good mulching mower but a poor grass collecting mower or vise versa. Accordingly, there is also a need for a mower of this type which has excellent performance in both modes of operation.